Biology Snippets

Wednesday, November 2, 2011

"Studies have suggested that drinking water has a thermogenic effect in adults that significantly increases their resting energy expenditure (REE), the calories required to maintain normal body functions in a resting state. Water-induced thermogenesis hadn't been tested in pediatric patients, researchers said."

Experts tell us that pulling "all nighters" rarely are effective in raising test grades. Newer research tells us that the best way to increase alertness is to drink a cup of coffee and then take a 15-20 minute nap. The nap clears the body of sleep inducing adenosine and gives just enough time for the caffeine to hit the blood stream.

Source:Psychophysiology. 1997 Nov;34(6):721-5.Suppression of sleepiness in drivers: combination of caffeine with a short nap.Reyner LA, Horne JA.

Monday, August 15, 2011

It appears that there are a lot of misconceptions about the accuracy of memory.The facts below came from the August 4, 2011 online Scientific American:

Here are four common incorrect assumptions about memory, held by some of the survey subjects, that experts say should be forgotten:

1. Memory works like a video camera, recording the world around us onto a mental tape that we can later replay.

Nearly two thirds (63 percent) of those in the random telephone survey said that they agreed with this model of a passively recorded memory. This notion runs counter to research that has shown events to be recalled based on “goals and expectations..."

2. An unexpected occurrence is likely to be noticed—even when people’s attention is elsewhere.

More than three quarters (77.5 percent) of people thought that this would be the case. Clearly, they are unfamiliar with the gorilla suit study. That work and other research have shown that unexpected—and even preposterous—details frequently go unnoticed, and thus do not make it into memory.

3. Hypnosis can improve memory—especially when assisting a witness in recalling details associated with a crime.

Most memory experts disagree with this statement, but more than half (55.4 percent) of the surveyed public thought that it was accurate. Courts have already steered away from accepting testimony that was gathered through hypnosis. And many studies have demonstrated that people under hypnosis—and even those who are not—can often be led by questioners to “recall” things that never occurred.

4. Amnesia sufferers usually cannot remember their identity or name.

Although soap operas might lead you to conclude otherwise, most common forms of amnesia interfere with the formation of new long-term memories—usually as a result of a major brain injury. The researchers cite the movie Memento as a reasonably accurate portrayal of the condition, but most popular portraits “depict amnesia as something more like a much rarer fugue state in which someone cannot remember who they are and suddenly take leave of their home and work,” they noted. Perhaps because of the prevalence of this blank-stare amnesia in television and movies, a whopping 82.7 percent of those surveyed shared this (incorrect) view of the condition.

The survey also found that nearly half (47.6 percent) of respondents said that once a memory is formed, it is set in stone. This is also not true, say the researchers: “Our memories can change even if we don’t realize they have changed,” Simons said.

Along these lines, more than a third (37.1 percent) of people thought that “confident” testimony from a witness should be adequate for a criminal conviction. However, many defendants who were later shown to be innocent via DNA testing had originally been convicted based on a faulty ID by an eyewitness. And as the researchers pointed out in their paper, being confident about your memory of an event is a good predictor of its actual accuracy, but “the link between confidence and accuracy across individuals is more tenuous, in part because people differ in their baseline levels of expressed confidence.”

A lesson to be gleaned from all of this might exonerate a group that might need all of the credibility it can get these days: politicians. “The extent of these misbeliefs helps explain why so many people assume that politicians who may simply be remembering things wrong must be deliberately lying,” Chabris said. But imperfect memories alone, of course, do not guarantee anyone is always striving to be deception-free.

But if there’s one thing to remember about the findings, it’s that “people tend to place greater faith in the accuracy, completeness and vividness of their memories than they probably should,” Simons said.

Tuesday, June 28, 2011

It appears that there is a lot of confusion about sun screen and the Food and Drug Administration (FDA) has attempted to help the consumer by making the label more clear and truthful.

The FDA has banned exaggerated claims about sunscreens' strength and durability. Even broad-spectrum sunscreen with an SPF over 15 cannot be called "sunblock," because no lotion entirely blocks the sun's rays. Nor can sunscreen products be labeled as waterproof or sweatproof: There is no sunscreen that stays completely on the body when exposed to water. At the most, a product may be water- or sweat- resistant.

Not only do sunscreens come off the skin (particularly when exposed to water or toweled off) but their chemical components break down over time. To preserve the efficiency of sunscreens, the products should be stored in a cool, dry place and replaced every year. In addition, they should be reapplied at least every two hours or more frequently if exposed to water or rubbed off. Under the new regulations, water-resistant formulas must say on the label how long the product will protect skin before needing to be reapplied, either 40 or 80 minutes.

In addition, the FDA proposed a rule that would cap advertised SPF at "50 +", because the evidence that more expensive, higher-SPF products provide more skin protection is lacking. Many who wear high-SPF sunscreen spend more time in the sun and reapply less frequently than those whose sunscreen has a lower SPF. As a result, they end up with both sunburn and possibly long-term skin damage. In addition, many misunderstand the meaning of SPF.Source:Scientific American: 6/27/11

Thursday, June 23, 2011

When the health department in Columbia, Mo., nixed a new flavor of ice cream laced with cicadas in early June from a local shop's menu, it wasn't because it's illegal to serve the winged insects to the public. "It's not really regulated," says Gerald Worley, the department's manager of environmental health, who adds, "I don't claim to be an expert on this." Nonetheless, Worley says he discouraged Sparky's Homemade Ice Cream proprietor Scott Southwick from selling the surprisingly popular flavor because Southwick "didn't really have a plan for how he would cook them," and Worley worried that the critters, which were collected from the ground, might make people sick. "We suggested that it would not be a good idea," says Worley. The first batch, in which the boiled bugs were covered with brown sugar and milk chocolate, then mixed in with an ice cream base of brown sugar and butter, had promptly sold out after the shop announced the flavor on its Facebook page.

As it turns out, cicadas have a long culinary history, and the emergence this spring of the noisy, 13-year-cyclical cricket-like insect in the Southeast and southern Midwest has brought a resurgence in cicada cuisine. Ashlee Horne of Nashville likes her cicadas sautéed in butter and garlic. Jenna Jadin of Washington, D.C., bakes them into banana bread, chocolate-chip cookies and rhubarb pie. Others like them dipped in chocolate for a sweet, crunchy snack. The inch-long bugs are widely consumed around the world, especially in East Asia, and are considered a delicacy among the Iroquois people in the U.S. Even the ancient Greek philosopher Aristotle gobbled them up: in his 4th century B.C. text Historia Animalium, he noted that the young nymphs are tastier than mature bugs, which have a harder exoskeleton, and that among adults, the egg-laden females are best. (See pictures of bug cuisine.)

So why all the fuss about eating cicadas today? "We make such a big deal out of this, but the biggest thing we have to deal with is human ignorance. They are no more germy than any other animal," says David George Gordon, author of The Eat a Bug Cookbook, who likes cicada nymphs as a pizza topping and says they have an asparagus-like flavor. Nymphs also have a chewy texture, while mature cicadas are crunchy and have more of a nutty taste, similar to that of peanuts or almonds. (See TIME's photo gallery of what the world eats.)

Entomologist Steve Murphree of Belmont University in Nashville says nymphs, which live underground for 13 years by sucking the sap of tree roots, are safe to eat raw after they emerge from the ground and shed their exoskeleton. Mature cicadas should be boiled while still alive to kill any bacteria, and already-dead cicadas should never be harvested because they could be decomposing. Also, anyone with allergies to shellfish, which belong to the same family as cicadas, should avoid the bugs altogether. (Read more about cicada ice cream.)

But bug eaters need to act fast. Once they emerge, the 13-year cicadas live for five weeks at most, according to Murphree. They can be found mostly on oak, hickory, apple and pear trees, where they lay their eggs. By the end of July, most of these so-called Brood XIX cicadas, also known as the Great Southern Brood, will have gone back underground. While the red-eyed bugs have already quieted down in Kentucky and Tennessee, the males' distinctive mating song is still piercingly loud in parts of Missouri and southern Illinois. (See the top 10 annoying sounds.)

But chances are you'll need to catch and cook them yourself, judging by the Columbia, Mo., health department's reaction to cicada ice cream. Good thing the Web is full of cicada recipes, along with tips on catching and preparing them. Meanwhile, the more timid among us can sit back and watch.Source Time Magazine: http://www.time.com/time/nation/article/0,8599,2078830,00.html

Thursday, June 16, 2011

Scientists already knew that single-cell organisms live in harsh, dark environments miles underground. But recently a multicellular organism, a worm, was found deep in rock nearly three-quarters of a mile underground. Nematodes are tiny worms known for being adaptable. The nematode the team found in the mine was a new species, and the scientists named it Halicephalobus mephisto.

That wasn’t the only discovery. A little more than half a mile down, the researchers found two kinds of nematodes already known to live on the surface. And more than two miles underground, the team discovered traces of nematode DNA in the water coming from cracks in the rocks.

Tuesday, June 14, 2011

The best answer to this question is from the June 13, 2011 Science News:

In a study, published online June 12 in Nature Genetics, shows that some individuals mutate faster than others. That means it may be fairly common for people to inherit a disproportionate share of mutations from one parent.

Researchers from an international collaboration known as the 1000 Genomes Project deciphered the genetic blueprints of six people from two families — a mother, father and child from each — and counted up the mutations inherited by each child. From there, the team calculated the human mutation rate.

“We all mutate,” says study coauthor Philip Awadalla, a population geneticist at the University of Montreal. “And the mutation rate can be extraordinarily variable from individual to individual.”

Combined with the results of three similar recent studies, the rate indicates that, on average, about one DNA chemical letter in every 85 million gets mutated per generation through copying mistakes made during sperm and egg production. The new rate means each child inherits somewhere in the neighborhood of 30 to 50 new mutations.

Since no one had ever directly measured the human mutation rate, the researchers weren’t sure how much variation to expect. But the scientists did anticipate that fathers would hand down more mutations than mothers, due to a well-known phenomenon called male mutation bias. The effect stems from the fact that females are born with all the eggs they will ever have, but males produce new sperm all the time. Each time cells divide to make new sperm there’s a chance mistakes will happen in the DNA-copying process.

One of the two families the researchers examined — a mother, father and child of European descent — followed the expected pattern; 92 percent of the new mutations inherited by the child came from the father. But in the other family — a mother, father and child of Yoruban descent — only 36 percent of the mutations came from the father, meaning that the mother had the higher mutation rate.

“That’s very unusual. It’s surprising,” says Adam Eyre-Walker, an evolutionary biologist at the University of Sussex in Brighton, England. That doesn’t mean that male mutation bias doesn’t exist in humans, just that some women have faster mutation rates and some men have slightly slower ones. On average, men still rack up more DNA changes per generation than women do.

The reason for the variation in mutation rate is unclear. Genetic factors may make some people more prone to getting mutations or could beef up mutation-fixing machinery in others. Environmental factors and the age of the parents at the child’s conception might also influence the mutation rate, says Peter Keightley, an evolutionary geneticist at the University of Edinburgh. More, and larger studies of this kind will be needed to determine how much people’s mutation rates vary between individuals.